After the last 2 winters, when I restart my TGB 50cc Key West, it won't run. I took the carb entirely apart and cleaned it. I removed the fuel valve and clean it. I changed the fuel filter. It appears that oil is coming out of the oil pump. It runs great idling and with some throttle, but shuts out at full throttle. If I release the throttle, it will run again but keeps on shutting off at full throttle. Any clue as to what is taking place and causing the problem?